The present application claims priority to Japanese patent application No. 10-348647, filed Dec. 8, 1998.
This invention relates to a tape cassette, and more particularly to a small-sized tape cassette such as DVC (Digital Video Cassette) or the like.
A conventional tape cassette is disclosed, for example, in Japanese Utility Model Publication 5-19897(U). The tape cassette of this type comprises a case body consisting of an upper case and a lower case for containing rotatably therein a pair of tape reels which are wound with a tape. The lower case is provided with partition walls for defining areas for the tape reels, and the tape reels are respectively positioned in the areas surrounded with the partition walls.
Also inside the case body, is slidably provided a reel brake which is adapted to engage with the tape reels. The reel brake is biased toward the tape reels by means of a spring (biasing member). A support shaft to which the spring is fitted is provided outside and close to one of the partition walls of the lower case. The reel brake is engaged with the tape reels by a spring force of the spring while the tape cassette is not in use (the tape reels are locked) to prevent a free rotation of the tape reels. On the other hand, when the tape cassette is in use, the reel brake is caused to slide against the spring force of the spring thereby to disengage the tape reels from the reel brake.
However, in the above described conventional tape cassette, especially in the small-sized DVC or the like, the support shaft for supporting the spring is positioned close to the partition wall. Therefore, when the spring is mounted on the support shaft by means of an automatic assembling machine, an assembling error is likely to happen, or in some cases, a tool of the assembling machine abuts on the partition wall, thus causing a damage to the partition wall. This will lead to a problem of a low productivity of the tape cassette.
There has been an additional problem that when a vibration or a shock is exerted to the tape cassette while it is assembled or used, an arm portion of the spring is disengaged from a back face of a main body of the reel brake, and accordingly, a function of the reel brake will be lost.
Therefore, it is an object of the present invention to provide a tape cassette, especially a small-sized tape cassette in which the biasing member of the reel brake can be assembled near the partition wall without interfering with a part of the tape cassette and the tool of the assembling machine, and in which also the biasing member and the reel brake may not be disengaged from each other.
In order to solve the above described problems, there is provided according to an invention, a tape cassette which comprises a case body consisting of an upper case and a lower case, and including partition walls for defining areas for tape reels which are wound with a tape-shaped medium to rotatably contain the tape reels, a reel brake for preventing a free rotation of the tape reels in engagement with the tape reels when the tape cassette is not in use, the reel brake being biased toward the tape reels by means of a biasing member and slidably arranged between a locked position and an unlocked position of the tape reels, and a support portion for supporting the biasing member provided outside and close to the partition walls of the lower case, characterized in that a cut-out is formed in one of the partition walls of the lower case near the support portion, which is partially lower in height, and a projection is formed in one of the partition walls of the upper case at a position confronting the cut-out of the lower case, both the cut-out in the lower case and the projection in the upper case engaging with each other when the upper case and the lower case is connected.
The partition wall near the support portion for supporting the biasing member is made lower in a form of a cut-out. This will prevent the interference of the tool of the automatic assembling machine with the partition wall, when the biasing member is mounted by means of the automatic assembling machine. Further, the cut-out of the partition wall of the lower case and the projection of the partition wall of the upper case engage with each other, after assembled, and the tape reels are securely partitioned by means of the partition walls of the upper case and the lower case.
Further, according to an invention, there is provided a tape cassette which comprises a case body consisting of an upper case and a lower case for rotatably containing tape reels which are wound with a tape-shaped medium, and a reel brake for preventing a free rotation of the tape reels in engagement with the tape reels when the tape cassette is not in use, the reel brake being biased toward the tape reels by means of a helical torsion coil spring and slidably arranged between a locked position and an unlocked position of the tape reels, characterized in that a winding portion of the helical torsion coil spring is inserted into a support shaft in the lower case, with one of its arms abutted on a back face of a main body of the reel brake and the other arm abutted on the lower case respectively, the back face of the main body of the reel brake being formed with a protrusion for preventing disengagement of the one arm of the helical torsion coil spring therefrom.
When one of the arms of the helical torsion coil spring abuts on the back face of the main body of the reel brake, the movement of the arm will be restricted by the projection provided at the back face of the main body. This will prevent the one arm of the helical torsion coil spring from disengaging from the reel brake.